(a) Technical Field
The present disclosure relates generally to vehicular seat temperature control systems, and more particularly, to thermal wave-based seat heating.
(b) Background Art
Heated seats were once considered a luxury item in vehicles, but in recent times their implementation in has become increasingly commonplace. Vehicle seat heaters typically utilize a heating coil placed beneath the seat cover of the vehicle. The heating coil, which acts as a resistor, includes a long element of wire through which electricity passes. The heating coil resists the electricity flowing therethrough. Consequently, the resistance causes friction that is released in the form of heat.
A typical seat heater is controlled by a relay that, when activated (e.g., by pressing a button), allows a small electric current to flow through a coil in the relay. When current flows through the coil, a magnetic field is created, which closes a nearby switch. This completes a circuit and sends electricity from the vehicle's battery to the seat heater.
Various techniques have been adopted to control the temperature of the seat. For instance, a thermostat can be installed within the seat cover to monitor the heat output. Once the thermostat senses that the seat has reached a target temperature, the thermostat sends a signal, automatically turning off the relay until the seat cools down. When the seat has cooled down sufficiently, the thermostat can trigger circuit elements to re-activate the seat heater. In this manner, the seat heater cycles on and off to keep the temperature of the seat within a tolerable range of the target temperature. In some cases, the target temperature can be controlled or modified through direct user feedback or other sensor feedback-based methods. For instance, a user can select a seat heating level (e.g., “high” or “low”) by pressing buttons on a steering wheel or seat bracket.
Notably, various studies have shown that human thermal sensation adapts to static thermal conditions. In the case of temperature, human sensation of heat is relatively lessened when exposed to a single, non-changing temperature. Conversely, human thermal sensation can be enhanced in response to a continually oscillating temperature (e.g., by delivering waves of heat or cool to the user), thereby producing a “thermal wave” effect. Therefore, thermal sensation and comfort can be enhanced by oscillating the temperature of a vehicle seat.